This invention relates generally to fluoroscopic x-ray machines, and in particular to a fluoroscopy machine having a head mounted display for providing a real-time x-ray image to a physician.
Early x-ray fluoroscopy machines employed a simple fluorescent screen that could be positioned on one side of a patient opposite an x-ray source. X-rays passing through the patient caused fluorescence of the screen to create an instantaneous or xe2x80x9creal-timexe2x80x9d x-ray image of the patient. The location of the screen clearly indicated the portion of the patient being imaged and the orientation of the image was, by necessity, always the same as that of the patient.
Although this system was simple and intuitive, a relatively high dose of x-rays was needed to produce an image on the fluorescent screen. For this reason, modern fluoroscopy machines have replaced the simple fluorescent screen, usually, with an image intensifier tube coupled to a video camera. The image intensifier tube employs the mechanism of electron multiplication to greatly increase the flux striking the fluorescent screen, significantly reducing the amount of x-ray exposure required.
The video camera serves to record the image and provides the additional benefit of permitting the x-ray beam to be positioned without regard to the location of the physician who no longer views the fluorescent screen directly, but instead, views a high resolution CRT-type display placed in a convenient location. In order that the display be easily viewed, it may be placed on a stand independent of the rest of the fluoroscopy machine to be positioned in the best viewing location, or supported on adjustable arms to be moved during the course of the fluoroscopic procedure. Nevertheless, the displays are inherently bulky and relatively difficult to reposition, thus hampering the mobility of the physician. For this reason, multiple displays may be placed at different locations around the patient to accommodate physician movement.
By separating the display from the fluorescent screen of the image intensifier, the x-ray image loses its context with the patient. Both the site and orientation of the imaged structure are no longer apparent. For example, the image may often be upside down or in mirror image with respect to the physician""s view of the patient and may rotate as the x-ray beam is repositioned as a result of the geometry of the fluoroscopy machine.
While the prior art has addressed the limited problem of image rotation through various means including motors for rotating the video camera with respect to the image intensifier, or by rotating magnetic yokes deflecting the electron beam on the CRT, such systems are imperfect and at best correct only for rotation caused by the movement of the fluoroscopy machine and necessarily fail to account for the movement of the physician which might desirably shift the orientation of the x-ray image.
What is needed is a display system that preserves the complete flexibility of x-ray beam orientation and physician location offered by modern fluoroscopy machines while restoring the intuitive relationship between the x-ray image and the patient found in early fluoroscopy machines.
The present invention employs a head-mounted electronic display, such as has been developed for virtual reality-type systems, to provide a fluoroscopic image in the physician""s changing field of view regardless of movement of the physician. The image may be manipulated according to the relative positions of the physician and the fluoroscopy machine to provide an intuitive relationship between the displayed image and the patient either in rotation, translation or apparent perspective.
Specifically, the present invention provides a fluoroscopy machine having an x-ray source producing a beam of x-rays along an axis, and a support arm having a first end attached to the x-ray source and a second end opposite the x-ray source along the axis, the support arm providing a space along the axis between the first and second ends sufficient to accommodate a human patient. An x-ray detector attached to the second end of the arm is positioned to receive the x-rays along the axis and to provide electronic image signals. A head-mounted display provides image optics producing an image from the electronic image signals and viewable by the physician wearing the head mounted display on his or her head.
It is one object of the invention to provide a fluoroscopy machine allowing complete freedom of movement by the physician without the need for multiple display systems or complex gimbaled or articulated display supports. The head-mounted display ensures that the x-ray image is always in the physician""s field of view.
The image optics may produce an opaque image blocking the receipt of light through the image from the physician""s field of view, or may be transparent to permit the passage of light through the image.
Thus, it is another object of the invention to provide hands free viewing of both the image and other areas of the physician""s field of view. When an opaque image is selected it may be displaced from the center of the field of view so as to be visible by eye movement alone.
The fluoroscopy machine may include an input representing an angle of rotation and may further include image processing electronics for rotating the image to the angle of rotation. The input may be the relative angular displacement between the physician""s field of view and a reference fixed with respect to the fluoroscopy machine or the patient.
Thus, it is another object of the invention to provide automatic correction of the image rotation to comport with the viewpoint of the physician as the physician moves with respect to either the fluoroscopy machine or the patient.
The fluoroscopy machine may include an input representing a translation, and may include further, an image processor for translating the image within the field of view of the physician based on that input. The input may be the relative displacement between the physician""s field of view and a reference fixed with respect to the fluoroscopy machine or the patient.
Thus, it is another object of the invention to allow the image to be electronically xe2x80x9cattachedxe2x80x9d to the patient or the fluoroscopy machine so as to provide an intuitive reference frame between the image and patient or fluoroscopy machine.
The fluoroscopy machine may include an input representing a skewing, and may further include an image processor skewing of the image as a function of the input. The input may be a relative displacement and orientation between the physician""s field of view and a predetermined image plane fixed with respect to the image intensifier or the patient.
Thus, it is another object of the invention to impose perspective effects on the image so that the image is not only attached to a reference point in the real world, but appears to conform to a reference plane as well so as to provide an xe2x80x9cx-ray visionxe2x80x9d type display.
The foregoing and other objects and advantages of the invention will appear from the following description. In this description, reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration the preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference must be made therefore to the claims for interpreting the scope of the invention.